Cooling after Winter Layover

[Simoniz]

Had by 3.0l Merc out of the water for 5 months for the winter during which time the block and manifold were drained of water.

Boat went back in the water today and initially, when idling round the marina it ran a bit warm on the temp gauge (185 deg F instead of the usual 175). when I reved the engine the temperature dropped back to around 135 in seconds and so I thought it was a simple air lock problem. Took the boat out for a medium fast run and the temp stayed rock steady around the 175 mark where it always was last season. After manoevring the boat back onto its parking position again at idle engine speed, I noticed that, once again, the temp was up around the 185 mark.

when the boat was out of the water I squeezed some of the hoses to check condition and could hear/feel a crusty deposit inside the hoses. Have I dislodged this deposit and is it now blocking something like the thermostat or is it a simple air lock problem that will disappear with a bit of use.

The system quickly filled with water so I dont suspect the water pick up pump in the drive and the motor didnt overheat with hard running so I think the engine driven water circulating pump must be OK too.

Any advice please?

 

[Don S]

Re: Cooling after Winter Layover

What year drive? When was the impeller in the pump replaced last?

 

[Bondo]

Re: Cooling after Winter Layover

Ayuh,....

I read that you pulled the boat, drained the motor, Stored it,+ Threw it back in the Water,.....

No mention of Any Annual Maintance.........

With Any boat,... When there are signs of an Overheat,....

The Impeller is the 1st place to Look......

A Semi-Trashed Impeller will move some water, especially at higher RPMs....

 

[Simoniz]

Re: Cooling after Winter Layover

Ayuh,....

I read that you pulled the boat, drained the motor, Stored it,+ Threw it back in the Water,.....

No mention of Any Annual Maintance.........

With Any boat,... When there are signs of an Overheat,....

The Impeller is the 1st place to Look......

A Semi-Trashed Impeller will move some water, especially at higher RPMs....

Thanks for the advice,

there was no mention of the mainenance work done as none of it is relevant to the cooling system.

 

[bruceb58]

Re: Cooling after Winter Layover

When was the impeller replaced last?

 

[Simoniz]

Re: Cooling after Winter Layover

When was the impeller replaced last?

I dont know, but this is the third season Ive had the boat so its not been done in that time. The boat is 8 years old and it may be that its still on the original impellor.

 

[Don S]

Re: Cooling after Winter Layover

Thanks for the advice,

there was no mention of the mainenance work done as none of it is relevant to the cooling system.

Well, there SHOULD have been some annual maintenance done to the seawater pump and the rest of the cooling system.
Here is from the owners manual, the OEM Service manual says the exact same thing.

 

[Simoniz]

Re: Cooling after Winter Layover

Ah I see.

Im now beginning to see my mistake and the problem is, the boat is now back in the water.

To be honest there was a carb problem on the boat and I started and ran the engine briefly (15 seconds) a couple of times with no cooling water attatched. I thought this would be OK from having a jetski where you could run the engine happily for 30 seconds or so out of the water.

Has this ruined / finished off the seawater pump? I would have thought that with a bit of wear to the impellor it would no longer actually make contact with anything like the housing?

I dont have my manual to hand at the moment. How big a job is it to replace the impellor?

Ta for advice so far.

 

[Fishermark]

Re: Cooling after Winter Layover

I started and ran the engine briefly (15 seconds) a couple of times with no cooling water attatched. Has this ruined / finished off the seawater pump?

Yep.

 

[Fishermark]

Re: Cooling after Winter Layover

Not too hard to change, as long as everything comes apart as it should. (Things can get corroded up if it hasn't been apart in awhile). Look around here for additional info:

http://www.mercstuff.com/howdoi.htm